Behavioral effects of intracerebrally administered catecholamines in mice and their modifications by some adrenergic blocking agents

Increasing doses of epinephrine (E), norepinephrine (NE) and dopamine (DA) were administered intracerebrally to mice.These drugs cause, at low doses (1–10 g/mouse) purely excitatory symptoms, while at high doses (30–100 g/mouse) they induce a biphasic syndrome, consisting of an initial period of excitation, followed by depression. In animals pretreated with -adrenolytics (yohimbine and phentolamine) the excitation caused by the low doses of the catecholamines was unaffected, while the running fits and the depression elicited by the high doses were attenuated or abolished.